Expansion of dynamic random access memories (DRAMs) to higher densities, to one Gbit or higher integration, requires materials of high dielectric constants, in order to be able to construct sufficiently large capacitors in the reduced available surface area on an integrated circuit chip.
Compound oxide type materials, especially ferroelectric or paraelectric materials such as Ba.sub.x Sr.sub.(1-X) TiO.sub.3 or PbZr.sub.x T.sub.(1-X) O.sub.3 (PZT) appear to be among the materials having sufficiently high dielectric constants as required by one Gbit DRAMs. These materials must be deposited on electrodes in electrical contact to semiconductor regions such as silicon or alloys thereof. The high dielectric materials can be deposited by a variety of methods, which often involve heating the temperatures above 500 degrees C. at a certain stage. The materials can also be exposed to higher temperatures during fabrication of the devices.
The processing of the capacitor structure should maintain the integrity of the device, and interaction between the high dielectric material and the components of the substrates on which it is deposited should therefore be avoided. Interaction with silicon and silicon dioxide should specifically be prevented.